1. Field of the Invention
The present invention relates to a colored curable composition, a method for producing a color filter, a color filter, and a solid-state image pickup device and a liquid crystal display device including the color filter.
2. Description of the Related Art
As a method for preparing a color filter to be used for a liquid crystal display device (such as a LCD) and a solid-state image pickup device (such as a CCD or a CMOS), a pigment dispersing method has been widely known.
The pigment dispersing method is a method for preparing a color filter by a photolithographic method using colored photosensitive compositions in which pigments are dispersed in various photosensitive compositions. Since patterning is performed by a photolithographic method, this method is considered to be a preferable method for preparing a color filter having high positional accuracy, a large area and high definition. When a color filter is prepared by the pigment dispersing method, a coating is formed by applying a photosensitive composition on a glass substrate using a spin coater, a roll coater or the like, colored pixels are formed by pattern-exposing and developing the coating, and a color filter is obtained by repeating these operations for each color.
As an example of a colored photosensitive composition using a pigment, a blue-colored composition for a color filter including a phthalocyanine pigment as described in Japanese Patent Application Laid-Open (JP-A) No. 2001-33616 has been known.
When a display device such as a liquid crystal display device or a solid-state image pickup device is prepared by providing a color filter using a pigment, a pigment having a finer particle size is required in view of improvement of contrast. This is due to a factor that a polarization axis is rotated by scattering, birefringence and the like of light by a pigment. When refinement of a pigment is insufficient, light is scattered and absorbed by the pigment, whereby light transmittance is decreased, contrast is decreased, and curing sensitivity during pattern exposing is decreased.
In particular, higher definition has been recently desired for a color filter for a solid-state image pickup device, but further improvement of resolution is difficult in a conventionally-used pigment dispersion system under the present circumstances. Namely, there are problems in that unevenness of color is caused by the effect of coarse particles in the pigment, and the like. Therefore, the pigment dispersion system is not suitable for applications in which a fine pattern having a pixel size of 1.5 to 3.0 μm-square is required such as a solid-state image pickup device.
In response to such circumstances, a technique using a dye instead of a pigment has conventionally been suggested. However, dyes have been known to be generally inferior to pigments in light resistance and heat resistance, and sometimes problematic in view of performance of a color filter. Furthermore, dyes have problems in that they have low solubility in a photosensitive composition, and in that they have low stability over time and precipitate in the state of a liquid preparation or a coating film.
In response to these problems, a colored curable composition using a dye including a dipyrromethene compound and a phthalocyanine dye in combination, which has excellent storage stability and is capable of forming a color filter having high light resistance, has been suggested (see, for example, JP-A No. 2008-292970).
Furthermore, a colored curable composition including a dye and a pigment in combination has also been known (see, for example, US Patent Application Publication No. 2008/0171271).
As mentioned above, with respect to a colored curable composition including a dye, it has been known that an effect that a color filter having excellent storage stability and high light resistance may be formed is obtained by selecting a dye to be used. However, under the present circumstances, further improvement of this effect is desired for higher definition and improved performance of a color filter.